ON JANUARY 20, both the United States and South Korea confirmed their first cases of Covid-19; Taiwan reported its first case the next day, and Singapore followed two days later. Epidemic parity began and ended there. By the end of March, those three Asian countries had largely contained at least the first wave of their outbreaks—and, not only that, had done so at relatively minimal cost to their citizens’ routine way of life. The same could scarcely be said of the US. The story behind this divergence was obvious: The governments of South Korea, Taiwan, and Singapore were prepared to test, to trace, and to isolate, and ours was not. Such a vast discrepancy in basic preparedness was, however, almost incomprehensible to many American observers—it seemed impossible to imagine that it could be that simple. The astounding national variance had to be explained by some hidden variable.